Java/C3/Calling-methods-of-the-superclass/English-timed
From Script | Spoken-Tutorial
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00:01 | Welcome to the spoken-tutorial on Calling methods of the super class. |
00:07 | In this tutorial, we will learn: when to use the super keyword |
00:13 | How to call methods of the super class |
00:17 | How to invoke the constructor of the super class. |
00:22 | Here we are using: Ubuntu Version 12.04 ,JDK 1.7 ,Eclipse 4.3.1 |
00:32 | To follow this tutorial, you must have basic knowledge of Java and Eclipse IDE. |
00:39 | You must also have knowledge of subclassing and method overriding in Java. |
00:45 | If not, for relevant tutorials, please visit our website. |
00:51 | A subclass can use a superclass data or method using the super keyword. |
00:58 | The super keyword :
refers to the instance variable of the parent class, is used to invoke parent class constructor, is used to invoke parent class method. |
01:13 | Now, let us go to the IDE and to the project we created earlier. |
01:19 | Let us go to the Manager class. |
01:22 | Now, come to the getDetails() method. |
01:26 | In the return statement, let us remove Name and Email. |
01:32 | Now, let us come to the Employee class. |
01:36 | This is the parent class or super class. |
01:41 | We already have a getDetails() method here. |
01:46 | This method returns the name and email. |
01:51 | So, we can use this getDetails() method in the Manager class. |
01:57 | We will call getDetails() method from the Employee class, inside the Manager class. |
02:04 | So, come to the getDetails() method in the manager class. |
02:10 | Inside the return statement, type: super dot getDetails() plus slash n Manager of getDepartment(). |
02:22 | Now, let me run the program. |
02:25 | We can see that we get the Manager details. Thus we can call the method of superclass inside the subclass. |
02:36 | Now let us come to the Employee class. |
02:41 | Let us include a constructor here. |
02:44 | So, inside the Employee class, type: public space Employee within brackets String name, String email_address . |
02:59 | Within curly brackets, type: this dot name is equal to name semicolon , this dot email_address is equal to email_address |
03:17 | Now, let us comment the setter and getter methods. |
03:23 | Inside the getDetails() method- instead of getName, type name , instead of getEmail, type email_address. |
03:37 | A subclass inherits all of the methods and variables from a parent class. |
03:44 | Note that it does not inherit constructors. |
03:49 | But, constructors can call the non-private constructors of its superclass. |
03:55 | We do this using the keyword super from the child class constructor. |
04:01 | We will see that now. |
04:04 | For that, come to the Manager class. We will include a constructor here. |
04:10 | So, type: public space Manager within brackets String space name comma String space email underscore address comma String space dept . |
04:30 | Then, within curly brackets, type: super within brackets name, email underscore address semicolon. |
04:44 | Then type: department is equal to dept semicolon. |
04:51 | Here we will comment the setter and getter methods. |
04:56 | Then, in the getDetails() method type: department instead of getDepartment. |
05:05 | Now, come to the TestEmployee class. |
05:09 | Comment the call to the setter methods. |
05:15 | Now, inside the call to the Manager constructor, type: within quotes Nikkita Dinesh, abc@gmail.com, Accounts. |
05:32 | Now, run the program. |
05:35 | We get the output as shown. We get the Manager details. |
05:40 | In this way, we can call the constructor of the super class. |
05:45 | In this tutorial, we have learnt: the super keyword ,calling the method of the super class and invoking constructor of super class. |
05:56 | As an Assignment-Open the previous assignment. Call the Vehicle class run method in the Bike class. |
06:04 | The output should be: The Vehicle is running. The Bike is running safely. |
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07:05 | This is Arya Ratish from IIT Bombay, signing off. Thanks for joining. |